Popular smoking articles, such as cigarettes, have a substantially cylindrical rod shaped structure and include a charge of smokable material, such as shreds or strands of tobacco material (i.e., in cut filler form), surrounded by a paper wrapper, thereby forming a tobacco rod. It has become desirable to manufacture a cigarette having a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element includes cellulose acetate tow circumscribed by plug wrap, and is attached to the tobacco rod using a circumscribing tipping material. Many cigarettes include processed tobacco materials and/or tobacco extracts in order to provide certain flavorful characteristics to those cigarettes.
Many types of smoking products and improved smoking articles have been proposed through the years as improvements upon, or as alternatives to, the popular smoking articles. Recently, U.S. Pat. Nos. 4,708,151 to Shelar; 4,771,795 to White et al; 4,714,082 to Banerjee et al; 4,756,318 to Clearman et al; and 4,793,365 to Sensabaugh, Jr. et al; and European Patent Publication Nos. 212,234 and 277,519 propose cigarettes and pipes which comprise a fuel element, an aerosol generating means physically separate from the fuel element, and a separate mouth end piece. Such types of smoking articles provide natural tobacco flavors to the smoker thereof by heating, rather than burning, tobacco in various forms. Generally, natural tobacco flavors and aromas are important for the taste, aroma, and acceptance of smoking products, including substitute smoking materials. Thus, the search for natural tobacco flavor additives or flavor substances is a continuing task.
For example, U.S. Pat. No. 3,424,171 describes a process for the production of a non-tobacco smokable product having a tobacco taste. Tobacco is subjected to a moderate (i.e. below scorching) heat treatment i.e., at from about 175.degree. to 200.degree. C. (350.degree. to 400.degree. F.), to drive off aromatic components. These components are trapped on adsorbent charcoal, and removed from the charcoal by solvent extraction. The smokable product disclosed is vegetable matter, treated with the mixture of tobacco aromatic components and the solvent.
Similarly, U.S. Pat. No. 4,150,677 describes a process for the treatment of tobacco which comprises the steps of: (1) contacting tobacco which contains relatively high quantities of desirable flavorants with a stream of non-reactive gas, under conditions whereby the tobacco is heated in a temperature range from about 140.degree. to 180.degree. C.; (2) condensing the volatile constituents of the resulting gaseous stream; and (3) collecting said condensate. The condensate may be used subsequently to flavor a smoking material in order to enhance the organoleptic qualities of its smoke.
British Patent No. 1,383,029 describes a method of obtaining tobacco aroma substances which comprises an extraction treatment wherein the components of the tobacco that are soluble in a suitable solvent are extracted and the residue is obtained after removing the solvent is subjected to heat treatment at a temperature from 30.degree. to 260.degree. C.
U.S. Pat. Nos. 5,038,802 to White et al. and 5,016,654 to Bernasek et al. disclose extraction processes which heat tobacco and then pass an inert atmosphere through the heating chamber to collect volatiles from the tobacco. The volatiles are then fractionated in downstream operations, which include liquid sorbents, cold temperature traps, and filters.
U.S. Pat. No. 5,235,992 to Sensabaugh proposes a process that involves heating tobacco (e.g., in a flowing gas stream) during a first staged heating to a first "toasting" temperature to drive off volatile materials, increasing the toasting temperature during a second staged heating, and separately collecting, as flavor substances, at least portions of the volatile materials driven off at the first and second toasting temperatures.
U.S. Pat. No. 5,121,757 to White et al. proposes a process for altering the chemical nature of a tobacco extract, in which tobacco material is extracted with a chemical solvent, the extract is contacted with an ammonia compound, and the ammonia-treated extract is subjected to heat treatment in a pressure-controlled environment (e.g., in a Parr bomb).
While these processes have produced flavor substances acceptable for use in many smoking articles, they have either not been suitable for some smoking articles, or have necessarily required the forming of a tobacco extract prior to the obtaining of the desired compound, or have required expensive or inabundant starting materials. Moreover, many of these processes required multiple steps of processing. These multiple steps can not only lead to increased cost but also result in significant loss of the flavorful and aroma compounds. Thus, there is need to provide efficient and effective processes for producing flavorful and aromatic components useful in the manufacture of smoking articles.